The various OTTD pathfinders are much better, and most users find complicated features intimidating, which is why TTDP-style restricted/programmable signals won't ever find their way into the OpenTTD trunk.
However, an implementation of programmable signals is available as a patch, and is included in Chill's Patchpack (which is what I play).
Well, I for one, enjoy the degree of control that TTDPatch's signalling provides for me. That said, it is good that something is available via Chill's Patchpack.
I've never played OTTD trunk, and you shouldn't let the lack of such features put you off when the code is so easy to patch (even if savegame/patch compatibility is utterly crap).
This assumes that one has the technical expertise to author such a patch or is able to enlist the services of someone willing to take on the challenge. Of course this is also true of TTDPatch.
As for TTDP development or the lack thereof, it has become too difficult to continue adding new features relative to the tiny userbase who might benefit and the relative ease by which features can be added to OTTD, which has definitively overtaken TTDP in most areas.
It's not so much a question of new TTDPatch features as it is one of maintenance such as DaleStan's recent attempt (r2367) which failed due to a broken TTDPatch compiler farm which just happens to be hosted by the OpenTTD complilation server.
No new developers have stepped up since I joined, as far as I can tell, and I no longer have the motivation to spend my time on this project. I stopped playing TTDP when I "finished" my long-running game, for which many of the features I added were specifically aimed at.
This is perfectly understandable.
As for 20 year old games under development, I play Total Annihilation from time to time, which is about 16 years of age now, and mod packs, a replacement engine, etc for that are very much active development and will be for quite some time, I suspect.
The perseverance of the best of the best.
There is no doubt that OpenTTD should be the competitive player's choice. Until features such as the reality offered by custom bridgeheads reach OpenTTD, in my opinion (and that of several others) TTDPatch remains the scenario creator's venue of choice.